I was just routinely loading a short list in my "Edit Posts" screen, and in this case a list that didn't fill up the entire screen. This left the bottom of the screen visible. And, I spied two new bits of colour at the bottom, that I never saw before.
It didn't look like an April Fools joke.
But before I could try it out, it was gone.
Watch your screens - I bet it will be back. It's just not here, right now.
Thanks for the rush, Blogger.
(Update 12/10): I was right - it came back. Looks permanent, now.